Measurements of 106Ru activity in thin samples

We have measured the systematic influence of coincidence summing between electrons and gamma-rays on the calculated activity of (106)Ru and developed a simple model for assessing this influence. In the model it is supposed that the number of electrons penetrating the attenuating layer of a material exponentially decreases with the thickness of the layer. When thin samples are measured close to a detector having a beryllium window, the influence may reach 20%. However, for homogeneous samples measured in plastic canisters the influence may be only a few percent.